Receiver-Autonomous Spoofing Detection: Experimental Results of a Multi-antenna Receiver Defense Against a Portable Civil GPS Spoofer

Abstract

In this work we demonstrate the use of a dual antenna
\nreceiver that employs a receiver-autonomous angle-ofarrival
\nspoofing countermeasure. This defense is
\nconjectured to be effective against all but the most sophisticated spoofing attempts. The technique is based
\non observation of L1 carrier differences between multiple
\nantennas referenced to a common oscillator.
\nWe first employ a moderately sophisticated spoofer to
\n"fool" a single-antenna civil receiver. We then deploy the
\nsame attack after augmenting the receiver with an
\nadditional antenna and with receiver-autonomous spoofdetection
\nsoftware. The work discusses the experimental
\nresults together with various issues related to sensitivity,
\nprobability of false alarm, impact of carrier multipath,
\nline-bias-calibration, and physical setup and security.
\nWe suggest that this work is important to the community
\nas it provides experimental validation of a low-cost
\ntechnique for receiver-autonomous spoofing detection.
\nFurthermore, the technique, when combined with physical
\nsecurity of the antenna installation, provides a strong
\ndefense against even a sophisticated attack.
\nThe receiver employed is an L1-only civil GPS receiver
\nwith multiple antenna capability. The GPS chipset
\nemployed is the venerable GP2015/GP2021 that has been
\nfreely available for over a decade. As such, this receiver is
\nrepresentative of many civil receivers in use today for a
\nvariety of applications. Multiple antennas are enabled
\neither through multiple independent RF front ends and
\ncorrelators or via antenna multiplexing into a single RF
\nfront end and correlator bank.